The intervertebral disc is a cartilaginous tissue with highly ordered architecture, consisting of layers of Type I/II collagen fibers with successive orientations of +30 and -30 degrees to the transverse plane. The tissue is susceptible to degeneration secondary to injury and aging, characterized by a loss of the preferential collagen orientation, and replacement of the healthy tissue with a fibrous isotropic matrix. Conventional MR techniques for diagnosing degeneration in the disc have relied on detection of signal changes associated with decreased water content. Diffusion tensor microscopy is expected to provide a novel, structure-based mechanism for detecting cartilage degeneration and remodeling. In collaboration with the Center's goals in developing the methodology of diffusion tensor microscopy, healthy and spontaneously degenerating intervertebral discs of guinea pigs will be studied. Efforts will be focused on obtaining high resolution diffusion-weighted micrographs of the tissue, and corroborating the eigenvectors of the diffusion tensor with independent histological examination.